The present invention is directed towards a navigational lighting system for watercraft, and more particularly, towards a lighting system that employs lights positioned about the watercraft to reduce glare to the operator of the watercraft and to increase visibility to other watercraft.
In the endeavor of night time boating, safe operation requires two things. First, night time boating requires that the operator be able to xe2x80x9cseexe2x80x9d into the darkness of night, which is defined in navigation literature as to xe2x80x9cmaintain proper lookoutxe2x80x9d. The lookout requirement is best attained if the boat were operated without lights. Second, night time boating requires that the boat xe2x80x9cbe seenxe2x80x9d by others in the darkness of night. This second requirement is defined in navigation literature as xe2x80x9cconspicuityxe2x80x9d. Conspicuity is best attained if the boat were lit brightly with numerous lights. The criteria for safety, therefore, is to xe2x80x9cseexe2x80x9d and xe2x80x9cbe seenxe2x80x9d. Historically, however, these two goals have been at cross purposes. The problem is glare, otherwise referred to as unwanted light. There are five types glare, including primary glare, secondary glare, reflected glare, water glare, and bloom.
Primary glare is that light which emanates from a bulb or from a lensed or focused light source that travels directly to the observer""s eye. Primary glare is the type of light observed by looking directly into the focused beam of a flashlight or at a bare bulb. With primary glare, the observer sees the full force of the illumination.
An example of secondary glare is light which is observed by looking at a flashlight from the front, but off to the side. With secondary glare, the observer sees the lens as a secondary source of emission, but does not see the full brightness of the beam or the bare bulb.
Reflected glare is the type of light which bounces back to the observer from an illuminated surface. With reflected glare, the observer sees different objects with different clarity depending upon the reflectivity, shape, color, distance, and orientation of the object. Reflected glare in the context of this invention is that which is coming from the hull of a boat, or its fittings, or people in the boat. Water glare is a type of reflected glare that is usually not a problem unless the water is whitecapping or the bow wake or stern wake is illuminated.
Bloom is a type of reflected glare that is readily observed when a bright beam pierces a hazy night. The haze that is in the beam is actually reflected light from small particles of dust or water in the light path. With bloom, the observer experiences different degrees of glare depending upon the clarity of the air and upon the lateral standoff distance of the observer relative to the beam. It is well known that on hazy nights, it is better to step off to the side of a spotlight so that the beam is at a distance away from the observer""s line of sight so as to minimize the adverse effects of bloom. Bloom is a problem, even on clear nights with relatively dim lights, if it impairs the driver""s night vision. Bloom can be considered as air glare. Secondary glare can become reflected glare, water glare, or bloom. Even reflected glare can become another reflected glare, water glare, or bloom.
It is appreciated that glare is undesirable as it impairs the operator""s ability to see out into the darkness as part of his duty to maintain proper lookout. On the other hand, navigation lights are required for conspicuity and to avoid collision.
Current Navigation Rules that attempt to address night time boating conditions are antiquated. These lighting rules were promulgated before high speed watercraft were available and when night boating was rare. These rules call for red, green, and white lights to be appropriately displayed. It is the white light, by virtue of its intensity and location, which causes the most problems associated with glare. Current regulations require that the white masthead light be positioned at least one meter above the red and green lights when the craft is in it""s xe2x80x9cnormal at restxe2x80x9d floating position. In addition, the vertical sector requirements are defined as the vertical angle subtended by the light emitted from the fixture. It is measured from the xe2x80x9cat restxe2x80x9d and xe2x80x9cunloadedxe2x80x9d condition of the craft relative to the horizon. When a planing craft is xe2x80x9cunder wayxe2x80x9d and passengers are in the craft, the vertical sector requirements are meaningless as the craft has assumed a new attitude and the navigation lights often shine above or below the intended horizontal plane. This results in an unsafe condition.
Separate lens covers over lights have been required ever since oil lanterns were used at sea, to both shield the flame, and to give appropriate color to the marker lights. Separate lens covers exacerbate the fugitive glare problem due to their secondary emission. The secondary emission only gets worse with time as the lens gets dirty or hazy. Lenses also tend to smear the intended sharp cutoff lines as required on the vertical and horizontal sector angles.
Forward looking white navigation lights with a 225 degree horizontal spread are referred to as masthead lights. Stern lights are white and currently require 135 degrees of horizontal coverage to the rear of the boat. On boats under 12 meters in length, it is permissible to combine the masthead light and the stern light into a single 360 degree xe2x80x9call aroundxe2x80x9d light. It also has glare problems. Red and green side lights are required to shine from dead ahead to 112.5 degrees to the rear on either side of the boat. Although these fixtures are available in red and green, they are not available in white.
Existing solutions specifically mount the all around light on a pole or mast, making it vulnerable to snagging on lines, ski tow ropes, and overhanging structures. This type of elevated mast mounting usually necessitates a telescopic or removable mast to protect the fixture from harm during daytime use. An application problem is that all fixtures are manufactured and certified to be mounted on a flat horizontal surface or on a flat vertical surface parallel to the fore to aft centerline of the craft. Boats rarely have a flat, truly horizontal surface or a truly vertical surface. Even boats that have a surface approximating those contours, those surfaces are usually not at the proper location on the boat to correctly display the lights.
Current regulations require that the fixture provide a horizontal fan of light correctly oriented relative to both the horizon and the fore to aft axis of the boat. The correct location for the lights is on the front half of the boat, and that surface is usually angled downward and inward due to the streamlined configuration of the hull. Prior art fixtures cannot perform as required, and are designed for vertical mounting only or horizontal mounting only and these locations are rarely found on modern boats. When a sloped surface on a hull also tapers inward, the correct mounting of prior art fixtures becomes impossible for the average user. Therefore, mounting a fixture designed for vertical or horizontal application on a surface which is neither vertical nor horizontal, totally defeats the intent of trying to maintain the strict light beam sector limits and results in an unsafe condition.
The vertical sector requirements are that the light shall be of full brightness from the horizon up and down for 5 degrees and taper off to not less than 60 percent brightness at plus or minus 7.5 degrees from the horizon. This is difficult to maintain on small craft even when the fixtures are mounted correctly.
Increasing the vertical sector requirements for better coverage causes the light to shine down into the craft and blind the driver, or to cast uselessly up into the night sky. Attempts to minimize the down cast light and resultant glare are addressed by the addition of a mask below the light. Other attempts have refined the vertical sector angles of emission significantly, but cause conspicuity problems if the light is installed at the incorrect angle relative to the hull, and can be exacerbated when the craft is under way.
Section 16 of the American Boat and Yacht Council (ABYC) acknowledges the glare problem and requires that the lights be located in a position to eliminate all direct or indirect glare from the light which could reach the operators eyes. It is not possible, however, to maintain the desired horizontal and vertical light pattern using current technology due, in part, to the secondary glare from the lens cover and the housing on the fixture. Secondary glare reflects off objects in the craft and adversely affects the driver""s night vision.